brucellosis risk assessment

An integrated Approach to Controlling Brucellosis in Africa - Addis Ababa, 29-31 Jan 2013Dr Bankolé /16

An integrated Approach to Controlling Brucellosis in Africa

Brucellosisrisk assessment

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Anani Adeniran Bankole, DVM & PhD

DLS - TOGO

Workshop: An Integrated Approach to Controlling Brucellosis in Africa, Addis Ababa, 29-31 January 2013


RISK ANALYSISINTRODUCTION

Tool to provide decision makers with an objective repeatable and documented assessment of the risk posed by a particular course of action

« Hazard identification »What can go wrong?« Risk assessment » How likely is it to go wrong?What would be the consequences of it going wrong?« Risk management »What can be done to reduce the consequences?

For Brucellosis . Import Risk . Brucellosis surveillance . Microbiological risk assessment

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IMPORT RISK ASSESSMENT

Hazard identification

Imported Commodity• Semen• Embryo

transfer• Milk products

(human contamination)

• Breeding female

OIE Handbook Volume 1, 2010

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IMPORT RISK ASSESSMENT(2)

Entry assessment

Release of Brucellosis via imported potentially infected cattle

Risk assessment

Exposure assessmentExposure of cattle to Brucellosis via imported potentially infected cattle

Example of importation of Brucellosis via breeding cattle

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IMPORT RISK ASSESSMENT(3)

Risk assessment (2)Consequence assessmentSeveral different outcomes possible:

No sufficient quantities to result in an infection with no infection or disease established

infection outbreak (within the herd, between herds)

Risk estimationQualitative or quantitativeCombination of preceding probabilities

Quantitative results1. Annual probability of importing brucellosis2. Expected number of infected imports

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Acceptable risk


DECISION TOOL FOR BRUCELLOSIS SURVEILLANCE

EXAMPLE: A quantitative risk assessment for the importation of brucellosis-infected breeding cattle into Great Britain from selected European countries

(Jones et al., 2004)

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•GB (OFB since 1991) import breeding cattle from OFB herds in Northern Ireland and Republic of Ireland (Non OFB) •Results of the risk assessment

Prediction to import brucellosis from •Northern Ireland every 2.63 years•Republic of Ireland every 3.23 years

Risk managementIntroduction of post-calving testing for all imported

animals apart from the routine testing


DECISION TOOL FOR BRUCELLOSIS SURVEILLANCE

EXAMPLE: A simulation model of brucellosis spread in British cattle under several testing regimes (England et al., 2004)

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•High costs associated with Brucella routine testing in GB

•Issue of reducing the level of testing raised

Following predictions, Policy-makers decided: Abortions notification very important No testing level reduction


MICROBIOLOGICAL RISK ASSESSMENT

• 2 examples or studies8

Historical reputation of safety of Fermented foodsMany outbreaks reported due to fermented food

consumption (Memish and Balkhy, 2004)

Quantitative microbiological risk assessment (QMRA): scientific bases for the control and management of food-borne diseases


HUMAN INFECTION RISK ASSESSMENT

Risk assessment of human brucellosis infection from consumption of raw cow milk sold by vendors in The

Gambia

• Hazard identification

• Brucellosis present in Gambia and Brucella isolation (HF)

• Isolation from milk reported by many authors (Hamdy and Amin, 2002; Ocholi et al., 2004)

• Associated with disease in humans (Jennings et al., 2007)

• Hazard characterization

• 10-100 Brucella = dose by aerosol through inhalation sufficient to initiate infection (Bossi et al., 2004).

• Oral route: no definite knowledge, 1 CFU/g or ml in foods might might initiate infection (Kuplulu and Sarimehmetoglu, 2004). 15 to 30 % survive after ingestion (Pappas et al., 2005)

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HUMAN CONTAMINATION RISK ASSESSMENT (MILK)

Exposure assessmentProbabilities at ≠ levels

Dose-response assessmentConcentration of Brucella

in 1 serving (50-100ml)

Concentration at ≠ levelsVariation in Brucella concT and pH Growth model

Dose-response Model from Binomial distribution (no treshold)

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HUMAN CONTAMINATION RISK ASSESSMENT (3)

Probabilities of infection when exposed to contaminated serving and unknownstatus serving

(More time)

fermented by

fermented by

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Risk characterization



Raw milk after Overnight fermentation contains, more Brucella than fresh milk (Plommet, 1988)

Sensitivity analysis: if 50% reduction of the probability of Brucella shedding in milk:

30% reduction of the probability of infection by contaminated serving

Control options

Action to be undertaken apart from boiling the milk and reducing the prevalence (control measures):

Reduction of Brucella shedding (farmers’ practices in Gambia)

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How Human Brucellosis Incidence in Urban Kampala Can Be Reduced Most Efficiently? A Stochastic Risk Assessment of Informally-Marketed Milk (Makita et al.,

2010)

Design stochastic risk models to • assess the risk of human brucellosis infection

through consumption of informally marketed raw milk potentially infected with Brucella abortus in Kampala

• Identify the best control options

Results• 12.6% of informally marketed milk in urban Kampala

contaminated at purchase• annual incidence rate estimate: 5.8 per 10,000 people

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Recommendations from the control options assessment

Assessment of control options by simulations assuming 90% of enforcement was achieved

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Risk reduction Annually avoided incidence


CONCLUSION

Risk analysis• Important tool in all decision-making in the

face of uncertainty– Animal and animal products import– Surveillance programs (choice between different

options)– Food borne brucellosis control options

• Need of good risk communication and commitment of policy and decision makers

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brucellosis risk assessment

Technology

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importation of brucellosis

brucellosis surveillance

quantitative risk assessment

risk assessmentprediction

dr bankoldecision tool

infection outbreak

probabilities of infection